Heart disease is the leading cause of death among Americans 65 and older and the second leading cause of death in the 45-64 age group. A substantial fraction of these deaths are due to acute myocardial infarction. Long-term beta blocker therapy after AMI is a proven method for reducing mortality, cardiovascular mortality, and repeat AMI. Short-term compliance with beta-blocker therapy is good and improving, but recent studies show that in the year after AMI compliance with beta-blocker therapy drops sharply: half or fewer of patients are compliant at one year post-AMI. Furthermore, little is known about the causes or consequences of this decline. Given the widespread age, sex, and racial disparities in treatment and outcome for heart disease, disparities in compliance may be particularly salient. In an observational, retrospective setting using claims data from a large health insurer, therefore, we aim to: 1) measure the difference in healthcare costs between patients compliant and non-compliant with long-term beta-blocker therapy post-AMI. 2) measure disparities in compliance based upon age, sex, race, income, and insurance status. 3) measure how compliance varies with the characteristics of a patient's physician and with the characteristics of the physician-patient interaction. 4) decompose the variation in compliance into physician-specific and patient-specific components. 5) measure differences in mortality, reinfarction, and readmission between compliant and non-compliant patients, in order to assess selection bias in our data.